I've got you covered, sp73.

May I know if are you trying to save invoices or record a receive payment? That way, we can provide a correct resolution to your concern.

Selecting Save and New to the previous invoice will automatically set that option to default when creating a new one.

We can check if this is a browser-related issue by signing into your QuickBooks Online (QBO) using a private browser (incognito). There are times that the browser is already full of frequently accessed page resources, causing some unusual responses.

Here's how:

• Google Chrome: Ctrl + Shift + N
• Safari 11 or newer: ⌘ + Shift + N
• Mozilla Firefox: Ctrl + Shift + P
• Microsoft Edge: Ctrl + Shift + P

Once logged in, try to save a transaction again to double-check.

If it's successful, return to your default browser and perform a clear cache to refresh the system. In addition, you may use other supported browsers to further isolate the issue.

Once confirmed and the issue keeps going, I'd recommend communicating with our Technical Support. They have available tools to investigate the main cause of the problem and provide you with another workaround. 

Additionally, I've added an article that'll help you on how to set up and transactions: Create recurring transactions in QuickBooks Online. Do come back and keep us posted in dealing with your sales transactions. The Community is always here to help.